This disclosure is generally directed to photoreceptors, photoconductors, and the like. More specifically, the present disclosure is directed to multilayered drum, or flexible belt imaging members, or devices comprised of a first layer, a supporting medium like a substrate, a photogenerating layer, and a charge transport layer, including a plurality of charge transport layers, such as a first charge transport layer and a second charge transport layer, an optional adhesive layer, an optional hole blocking or undercoat layer, and an optional overcoat layer, and wherein the supporting substrate is situated between the first layer and the photogenerating layer. More specifically, the photoconductors disclosed, which in embodiments permit acceptable anticurl characteristics in combination with excellent conductivity, prolonged wear, surface slipperiness, and scratch resistant characteristics, contain a first backside coating layer or curl deterring backside coating layer (ACBC), and which layer is in contact with and contiguous to the reverse side of the supporting substrate, that is this side of the substrate that is not in contact with the photogenerating layer, and which first layer, ACBC layer of the present disclosure, is comprised of nano diamond and nano diamond components, such as in the form of nano diamond powders.
The ACBC layer of the present disclosure comprises a diamond component and a slippery surface, thus the wear resistance of this layer is excellent, especially as compared to an ACBC layer without any nano diamond, or an ACBC layer containing a polytetrafluoroethylene (PTFE). Also, the coating dispersion containing the nano diamond component is stable for extended time periods; minimal agglomeration of the ACBC layer components is provided, thereby increasing the coating uniformity of this layer; and other advantages as illustrated herein for photoconductors with ACBC layers comprising a nano diamond component.
While not being desired to be limited by theory, it has been postulated that the dispersed nano diamond powder provides a matrix of conductive nanoparticles that contact each other to thereby generate reasonable levels of electrical conductivity, while not filling all the void matrix spaces, thus permitting the transmission of light. The aforementioned partial transparency of about 30 percent allows for excellent photoreceptor applications since the erase illumination is applied from inside the belt module and passes through the ACBC into the photogenerating layer. The electrical conductivity allows the triboelectrically generated charges to move through the layer and discharge before the quantity of charge builds up to significant levels. The nano diamond provides additional mechanical reinforcement which reduces wear, thus minimizing dust buildup.
In some instances, when a flexible layered photoconductor belt is mounted over a belt support module comprising various supporting rollers and backer bars present in a xerographic imaging apparatus, the anticurl or reduction in curl backside coating (ACBC), functioning under a normal xerographic machine operation condition, is repeatedly subjected to mechanical sliding contact against the apparatus backer bars and the belt support module rollers to thereby adversely impact the ACBC wear characteristics. Moreover, with a number of known prior art ACBC photoconductor layers formulated to contain non-needle like additives, the mechanical interactions against the belt support module components can decrease the lifetime of the photoconductor primarily because of wear and degradation after short time periods.
In embodiments, the photoconductors disclosed include an ACBC (anticurl backside coating) layer on the reverse side of the supporting substrate of a belt photoreceptor. The ACBC layer, which can be solution coated, for example, as a self-adhesive layer on the reverse side of the substrate of the photoconductor, comprises known nano diamond components, such as commercially available nano diamond powders that, for example, substantially reduce surface contact friction, and prevent or minimize wear/scratch problems for the photoreceptor device. In embodiments, the mechanically robust ACBC layer of the present disclosure usually will not substantially reduce the layer's thickness over extended time periods adversely affecting its anticurl ability for maintaining effective imaging member belt flatness while minimizing the formation of dirt and debris.
Moreover, high surface contact friction of the backside coating against machines, such as printers, and its subsystems can cause the development of undesirable electrostatic charge buildup. In a number of instances, with devices, such as printers, the electrostatic charge builds up because of high contact friction between the anticurl backside coating and the backer bars which increases the frictional force to the point that it requires higher torque from the driving motor to pull the belt for effective cycling motion. In a full color electrophotographic apparatus using a 10-pitch photoreceptor belt, this electrostatic charge buildup can be high due to the large number of backer bars used in the machine.
The backside coating layers illustrated herein, in embodiments, have excellent wear resistance, extended lifetimes, minimal charge buildup, excellent bulk conductivity, and permit the elimination or minimization of photoconductive imaging member belt ACBC scratches.
Also included within the scope of the present disclosure are methods of imaging and printing with the photoresponsive or photoconductor devices illustrated herein. These methods generally involve the formation of an electrostatic latent image on the imaging member, followed by developing the image with a toner composition comprised, for example, of thermoplastic resin, colorant, such as pigment, charge additive, and surface additive, reference U.S. Pat. Nos. 4,560,635; 4,298,697 and 4,338,390, the disclosures of which are totally incorporated herein by reference, subsequently transferring the toner image to a suitable image receiving substrate, and permanently affixing the image thereto. In those environments wherein the device is to be used in a printing mode, the imaging method involves the same operation with the exception that exposure can be accomplished with a laser device or image bar. More specifically, the flexible photoconductor belts disclosed herein can be selected for the Xerox Corporation iGEN® machines that generate with some versions over 100 copies per minute. Processes of imaging, especially xerographic imaging and printing, including digital and/or color printing, are thus encompassed by the present disclosure. The imaging members are, in embodiments, sensitive in the wavelength region of, for example, from about 400 to about 900 nanometers, and in particular from about 650 to about 850 nanometers, thus diode lasers can be selected as the light source. Moreover, the imaging members of this disclosure are useful in color xerographic applications, particularly high-speed color copying and printing processes.